Musk's Hyperloop Explained: 760 mph on Paper, Not 4,000

The short answer: 760 mph on paper, not 4,000

The Hyperloop that Elon Musk proposed in 2013 was never designed to reach 4,000 miles per hour. The official design paper, Hyperloop Alpha, set a top capsule speed of about 760 mph (roughly 1,220 km/h), just under the speed of sound, with an average closer to 600 mph over a trip from Los Angeles to San Francisco of about 35 minutes. That figure was a proposal on paper. More than a decade later, no passenger hyperloop is running anywhere.

The 4,000-mph figure spread widely in 2013 headlines. Below is what Musk actually said, how the system was meant to work, where the bigger number probably came from, and what happened to the idea.

The 2013 Hyperloop Proposal: Correcting the 4,000-mph Claim

From a teaser to the Alpha paper

Musk first floated a "fifth mode of transport" in 2012, saying it would beat planes, trains, cars and boats, but he gave few details. At the D11 technology conference in May 2013 he described it, in a much-quoted line, as "a cross between a Concorde and a railgun and an air hockey table." He also suggested it could be about twice as fast as a typical airliner on short routes and leave whenever passengers were ready rather than on a fixed timetable.

The vague hints set off months of guessing. Brian Dodson, a physicist writing for Gizmag, ruled out a full vacuum tunnel and an electromagnetic launch loop and argued that the plan was probably pneumatic, a closed tube looping between the two cities, a reading picked up by Discovery News. The popular comparison was with the capsules that shoot through pneumatic tubes at bank drive-throughs.

The real details came on 12 August 2013, when Tesla and SpaceX published the 57-page Hyperloop Alpha paper and invited others to develop the idea, since Musk said he was too busy to build it himself.

How the design was supposed to work

The guessers were partly right. There would be a tube, but the capsules would not be blown along by air pressure. Instead, Alpha described:

A low-pressure tube. Air would be pumped down to around one-thousandth of normal atmospheric pressure, not a full vacuum, cutting drag while keeping the pumps practical.
Air bearings. Each capsule would float on thin cushions of pressurised air, the "air hockey table" part of Musk's description.
A nose compressor. A fan at the front would move air from in front of the capsule to behind it, so the capsule would not push a growing column of air down the tube.
Linear electric motors. Short sections of track would accelerate and slow the capsules, the "railgun" part.
Solar panels on top of the tube, which would run on pylons largely beside Interstate 5.

Musk framed the paper partly as a response to California's planned high-speed rail line, which he criticised as too slow and too expensive for the distance of roughly 350 miles between the two cities. A cheaper, faster alternative was the central promise of Alpha, and it is the claim later critics examined most closely.

Capsules were to carry 28 passengers and depart as often as every couple of minutes. The paper estimated the cost of a passenger-only line at about $6 billion, and around $7.5 billion for a larger version able to carry cars.

Where the 4,000-mph figure probably came from

The bigger number did not appear in Musk's plan. It most likely came from older evacuated-tube transport concepts. ET3, a Colorado-based project promoted before Musk's announcement, reportedly spoke of speeds up to 4,000 mph for long international routes in a fully evacuated tube. In 2013 headline writers often blended the two ideas, and the larger figure travelled faster than the correction.

It is a useful lesson in reading technology news: when a headline quotes a dramatic speed, look for the original design document and check whether the number is a measured result, a design target or someone else's speculation.

What happened after 2013

For a few years the idea boomed. SpaceX ran a pod-design competition for university teams from 2015 to 2019, and the winning team from the Technical University of Munich pushed its small, unmanned pod to about 463 km/h (288 mph) on a short test tube in 2019.

The best-funded company, Hyperloop One, later branded Virgin Hyperloop, carried two employees in a test pod in November 2020 at about 107 mph (172 km/h) on its Nevada test track. It never secured a contract to build a working line. The company shifted its focus to cargo, dropped the Virgin name, and at the end of 2023 laid off its remaining staff and began selling its assets. Smaller firms in Europe and elsewhere have continued testing prototypes, but none has opened a commercial route.

Why the idea stalled, and what it still offers

Engineers and transport economists raised doubts from the start. The $6 billion estimate was widely criticised as far too low for an elevated line across California's earthquake country. Keeping hundreds of kilometres of tube at low pressure, handling the expansion of steel in the sun, getting passengers out safely in an emergency, and keeping turns gentle enough for comfort at near-sonic speed all proved harder than the white paper suggested.

Musk himself reportedly hedged in 2013, saying that even if he was "sort of wrong about the economic assumptions behind the Hyperloop, it would still be a really fun ride." That turned out to be the fairer summary. The Alpha paper did spark a decade of student engineering, test tracks and debate about low-drag travel, and parts of the research, such as magnetic levitation and linear motors, already exist in other transport systems. A 4,000-mph tube train, though, was never part of the plan.